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(No ModeL) 2 Sheets-Sheet 1. A. BLONDEL & S. PSAROUDAKI.

REFLECTOR.

No. 593,348. Patented Nov. 9, 1897.

INVENTOR S RTTORNEY wwr 7h. 7 fan! (No Model.) 2 Sheets-Sheet 2 A. BLONDEL & S. PSAROUDAKI.

REFLECTOR.

No. 593,348. Patented Nov. 9, 1897.

WITNESSES: INVENTORS 7 17%;

74 /QT, Q6 %/6 ATTORNEYS UNITED STATES PATENT ()EEIcE.

ANDRE ULONDET. ANT) SPIRIDION PSAROUDAKI, OF PARIS, FRANCE, AHSIGNORS TO LOUIS N. BRUNER.

REFLECTOR.

SPECIFICATION forming part of Letters Patent No. 593,348, dated November 9, 1897.

Original application filed March 30, 1895, Serial No. 543,921. Divided and this application filed May 29, 1896. Serial No. 593,653. \No model.) Patented in Germany March 16,1893,N0. 78,866; in England October 12, 1893,110. 19,185; in Austria-Hungary January 6,1894, No, 48,988; in Belgium March 13, 1894,110. 108,985, and in France September 30,

To all whom, it may concern.-

Be it known that we, ANDRE BLONDEL, a citizen of France, and SPIRIDION PSAROU- DAKI, a citizen of Turkey, residing at Paris, France, have invented certain new and useful Improvements in Reflectors; and we do hereby declare the following to bc a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being bad to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

This invention has been patented in France September 30, 1806, No. 233,140; in Austria- ]Iungary January (3, 1804, No. 5,988; in Germany March 16, 1893, No. 78,803; in England October 12, 1893, No. 19,185, and in Belgium March 1 3, 1891, No. 108,985.

Our invention relates to a globe or disk shaped reflector made entirely of clear glass and designed to be a perfect 1nirror-that is to say, to reflect all light falling upon it. It is made, preferably, in the form of a segment of a sphere, but it may be of other forms, such as curved or straight tapering. The object is to cause complete reflection of light by its refraction and reflection. Our reflector may be made independent for use alone or it may be molded as a part of a globe. Our reflector is formed with a series of concentric triangular prisms upon the outer or convex surface of the reflector and triangular prisms upon the inner or concave surface at right angles to those upon the convex surface.

Figure 1 is a vertical elevation of the reflector, looking upon its concave surface. Fig. 2 is a vertical elevation viewing the convex surface. Fig. 3 is a sectional view of the reflector on an enlarged scale, showing the form of the exterior prisms. Fig. 4 is a section of the reflector on a large scale, showing the form of the interior prisms. Fig. 5 is a vertical section of a reflector designed to throw the light upward, as shown in the drawings.

Referring to Fig. 1, it will be seen that the prisms in that figure radiate from the center of the convex surface and are triangular in shape.

V'ewing Fig. :2, it will be seen that the external prisms are concentric and described from the same center as the center from which the interior prisms radiate.

Viewing Fig. 4, the ray a enters the glass of the interior prism by refraction, penetrates the glass, and strikes upon the exterior sur face of the external prism at it. There it is reflected to the opposite surface of the same prism at Z), and thence returns through the glass and out of the interior prism by refraw tion at Z).

Viewing Fig. 5, which is a vertical section of a reflector embodying our invention, the exterior surface A B (1 has upon it triangular prisms which are concentric and which in the position shown in that figure are horizontal, while the interior prisms are vertical, being largest at the largest diameter of the reflector and reducing in size to their center, where they disappear.

This application is a division or portion of the application, Serial No. 513,921, to us for lamp-globes, which has since been issued as Patent No. 563,836.

For the purpose of clearness we insert a form of calculation which we have used in determining the profiles of the interior and exterior triangular surfaces.

Referring to the drawings, Fig. (i represents a section of an interior prism; Fig. '7, a section of an exterior prism, and Fig. 8 an interior prism. Rays of light are indicated by solid lines and angles by dotted lines.

Let a b c and g h 71, Figs. 6 and 8, represent the profiles of the interior triangular surfaces, and d e f the profile of an exterior triangular surface. Let 1 represent the ray before it is refracted by the surface a b, and 2 the ray after refraction, a the angle of incidence, y the angle of refraction, and o the angle of deviation from the direction 1.

From Fig. U the angle of deviation is given by the equation Whenee (l) Sin. r5 sin. (r A sin. a cos. cos. (1' sin. 1.

From the law ol refraction we have 1 bin. 7

sin. 1r,

whereuequals theindexotrefractionforlight when passing from glass into air. \Vhence 1 70s. y l v sin. -y :Jl a sin. 2 (r.

Substituting these values of sin. 7 and cos. y in (l), we have Sin. 6 sin.1r /1 w snr zr cos. n SH]. (1 or n 1 2 1 Sin. 6 sin. n l- ,,s1n. a cos. (Y.

From this equation we may compute a useful table of values of 6 corresponding to determined values of (1 For example, a table for the case of n follows:

Table l.

r F 0 Y I! n 1U d 3 22 24 3t! 46 4t) Lil ll 3 3-") 12 25 ltl 14 4-2 51 4] 15 5 4t! 4] lb 15 37 (r (Y and Since it is desired that the rays should not be refracted on these surfaces, it is only neces' sary to so draw them that the angles of incidence a and 0/ will be greater than forty five degrees. Having drawn the surfaces (Z c and e fso as to give the desired direction -t of the ray, all that is now necessary is to draw the surface It 'i of the interior profile Fig. 8 in such a direction as to give the desired direction 5 of the ray after refraction. Let 4 be the direction of the ray in the glass before coming to the surface h 1, 11' the angle ol incidence,y he angle of refraction, and i the angle otdeviation from the direct ion 4. From the figure \Vhence 3 Sin. 6 2 sin. I 7 1r l 1| l.

sin. y, cos. a, cos. y, sin. 14

From the law of refraction we have Sin. y. n sin. (r

wherenequals thcindexoi" retraction forlight when passing from glass into air. Whenee Substituting these values of sin. y. and cosy in equation we have Sin. 6,:22 sin. (1, cos. n',sin.o l l2 sink a.

Sin. 6, sin. a, (11 cos. (1', fl 'H 'EinJ- a From this equation we may complete a useful table similar to Table I of values of 6. corresponding to determinate values of Ir For example,

Table II.

D I U I ll 2 t 3] ill 41 :JH hi Now from this table we can draw the prolile h i in such a way to get any desired angle of deviation 6 For the retracting surfaces shown in Figs. 6 and S it is necessary to draw them so that there will be no reflection of the rays, and this is accomplished by placing them at such an angularity with the rays 1 and 4 that the angles of incidence (v, and a, are less than forty degrees. Since the triangular surfaces are small, all 01". the rays striking any one of them are supposed to be par' allel. This makes the construction quite sim ple, as all the rays coming in contact with any surface remain parallel after both re fraction or reflection.

To construct the retracting and reflecting surfaces in the manner above explained, the diifusion of the light is of course predetermined. In other words, the directions 5 of the rays after the last refraction are predetermined. It is then only necessary to construct the surfaces in such a way as to give the predetermined directions to the rays.

Having thus described our invention, what we claim, and desire to secure by Letters Patright; angles to the flutine's on the other taee and the profiles of said tlutings heing trian gular.

2. A retleetor made of. clear or ll'tillSllI'tl't'Hl glass, a portion of \\'lll('ll is provided on its exterior with horizontal tlutiugjs, the proliles of which are triangular and the interior surface of which is provided with a series of vertical ilntings, the profiles of which are triangular.

3. A relleetor made of elear or transparent glass which is convex on one side and eoneave 0n the other, and having tlntings on its (-oneave and convex surfaces, said tinting-a:

l)eing arranged at about right angles to one another, the profiles of said [hit in heingtriangular.

4. A reflector made of elea r or transparent glass concave on one side and eonvex 0n the other, havingtriangular eonventrie prisms npon its convex surtaee, and having," tlutiug's upon its eoueave surfare \vhit-h radiate from theeeuter of the eireles ot tho evterior prisms. 3. A retleetor made of elear or transparent glans, lltflllg oneavo upon one HitlO and eonvex upon the other, having triangular eoneeutrie prisms ot' unit'orin shape on its Convex sin-fares, and having on its eoneave surface a series of triangular prisms \vhieh radiate from the center ot. the rireles of the exterior prisms.

In testi monv whereof \ve atli X ouraignatures in presenee of two witnesses;

ANDRE HLUNDEL. SlllilhlUN .lSA] (lllL\l\'I. J itnesses:

G. on Mns'rnvh, (rvnn SHLHISI RF. 

